Enhancing Color Images

• US 20110285746A1
• Filed: 10/19/2010
• Published: 11/24/2011
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Swic, Jerzy Wieslaw
• Granted Patent: US 8,565,522 B2
• Time in Patent Office: Days
• US Class Current: 345/597
• CPC Class Codes: G09G 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 25/133 including elements passing panchromatic light, e.g. filters passing white light
• CPC Class Codes: H04N 25/135 based on four or more different wavelength filter elements
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86
• CPC Class Codes: H04N 9/77 Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase circuits for matrixing H04N9/67

Abstract

A method for enhancing a color image may include selecting a set of operations from a group of operations, specifying an order for performing the selected set of operations, receiving the color image, and performing, with a processor, the selected set of operations in the specified order on the color image. The group of operations may include a color correcting operation, an image filtering operation, a color linearization operation, a saturation adjustment operation, a luma scaling operation, and an image dithering operation. The method may include determining an optical property of an ambient light source or an image type of the color image. The selecting of the set of operations may be based at least in part on the determined optical property of the ambient light source or on the determined image type. The method may include an efficient method for correcting image saturation of a color image.

Claims

1. A method for enhancing a color image, comprising:

selecting a set of operations from a group of operations, the group of operations including a color correcting operation, an image filtering operation, a color linearization operation, a saturation adjustment operation, a luma scaling operation, and an image dithering operation;

specifying an order for performing the selected set of operations;

receiving the color image; and

performing, with a processor, the selected set of operations in the specified order on the color image.

2. The method of claim 1, further comprising:

determining an optical property of an ambient light source, wherein

the selecting of the set of operations is based at least in part on the determined optical property.

3. The method of claim 2, wherein the determining the optical property of the ambient light source includes sensing an optical property of the ambient light source with an image sensor.

4. The method of claim 1, further comprising:

determining an optical property of an ambient light source; and

determining a parameter to be used by one of the selected operations at least in part from the determined optical property.

5. The method of claim 1, further comprising:

determining an image type of the color image, wherein

the selecting of the set of operations is based at least in part on the determined image type.

6. The method of claim 5, further comprising:

determining two or more image types of the color image, wherein

the selecting of the set of operations includes selecting a first set of operations for a first image type and a second set of operations for a second image type, the selecting of the first and second sets of operations being based at least in part on the determined first and second image types.

7. The method of claim 1, wherein the processor performs at least a first one of the selected set of operations in parallel with at least a second one of the selected set of operations, further comprising:

determining a latency associated with each operation in the selected set of operations; and

delaying a result of a faster operation so that a latency of the faster operation matches the latency of a slower operation.

8. The method of claim 1, wherein the color image is defined by two or more data pixels, each data pixel having a red, green, and blue color component, and the saturation adjustment operation includes:

receiving a first data pixel of the color image;

calculating a luma component for the first data pixel;

determining first, second, and third differences by subtracting the luma component from the red, green, and blue color components of the first data pixel;

determining first, second, and third products by respectively multiplying the first, second, and third differences by first, second, and third adjustment factors; and

determining saturation-adjusted red, green, and blue color components by adding the first, second, and third products to the luma component.

9. A method for correcting image saturation of a color image, the color image being defined by two or more data pixels, each data pixel having a red, green, and blue color component, comprising:

receiving a first data pixel of the image;

calculating, with a processor, a luma component for the first data pixel;

determining first, second, and third differences by subtracting the luma component from the red, green, and blue color components of the first data pixel;

determining first, second, and third products by respectively multiplying the first, second, and third differences by first, second, and third adjustment factors; and

determining saturation-adjusted red, green, and blue color components by adding the first, second, and third products to the luma component.

10. The method of claim 9, wherein the first, second, and third adjustment factors are equal to a constant.

11. The method of claim 9, wherein the first, second, and third adjustment factors are respectively equal to first, second, and third constants.

12. The method of claim 9, wherein the first, second, and third adjustment factors are a function of the red, green, and blue color components of the first data pixel.

13. A processor for enhancing a color image, comprising:

an interface to receive the color image; and

a color processing unit to;

select a set of operations from a group of operations, the group of operations including a color correcting operation, an image filtering operation, a color linearization operation, a saturation adjustment operation, a luma scaling operation, and an image dithering operation;

specify an order for performing the selected set of operations;

perform the selected set of operations in the specified order on the color image.

14. The processor of claim 13, wherein the color processing unit receives a determination of an optical property of an ambient light source, and selects the set of operations based at least in part on the determined optical property.

15. The processor of claim 14, wherein the color processing unit receives a determination of the optical property of the ambient light source from an image sensor.

16. The processor of claim 13, wherein the color processing unit receives a determination of an optical property of an ambient light source, and determines a parameter to be used in performance of one of the selected operations at least in part from the determined optical property.

17. The processor of claim 13, wherein the color processing unit determines an image type of the color image, and selects the set of operations is based at least in part on the determined image type.

18. The processor of claim 17, wherein the color processing unit determines two or more image types of the color image, and selects a first set of operations for a first image type and a second set of operations for a second image type, the selecting of the first and second sets of operations being based at least in part on the determined first and second image types.

19. The processor of claim 13, wherein the color processing unit performs at least a first one of the selected set of operations in parallel with at least a second one of the selected set of operations, and the color processing unit:

determines a latency associated with each operation in the selected set of operations; and

delays a result of a faster operation so that a latency of the faster operation matches the latency of a slower operation.

20. The processor of claim 13, wherein the color image is defined by two or more data pixels, each data pixel having a red, green, and blue color component, and performance of the saturation adjustment operation by the color processing unit performs includes:

receiving a first data pixel of the color image;

calculating a luma component for the first data pixel;

determining first, second, and third differences by subtracting the luma component from the red, green, and blue color components of the first data pixel;

determining first, second, and third products by respectively multiplying the first, second, and third differences by first, second, and third adjustment factors; and

determining saturation-adjusted red, green, and blue color components by adding the first, second, and third products to the luma component.